Investigate renaming replace expression language method

As explored in NIFI-1919, the expression language string replacement methods could be more clearly named to differentiate their actions – the difference between replace and replaceAll is not their frequency of operation, but rather that replace accepts only literal strings, while replaceAll interprets the provided search pattern as a regular expression.

Related, the ReplaceEvaluator, ReplaceAllEvaluator, and new ReplaceFirstEvaluator classes differ only by one line for each respective operation. It may be possible to refactor this to remove duplicate code.